Quandaries
and Queries 

does anyone have a formula for calculating the length of an arc if I have the circle radius and the cord length of the arc?? Thanks Gavin 

Hi Gavin, If M is the midpoint of the chord as in the diagram
then PCM is a right triangle. Hence the angle PCM has sine ^{MP}/_{PC}.
Since you know the radius PC, and MP is half the chord length, you can find sin(anglePCM). Use the inverse sine function to find this angle in radians and then double it to find the angle PCQ. The length of the arc is given by Penny 

